Field of the Invention
Shoes should protect the human foot from injury, shield it from cold and heat, reduce shocks to the skeleton when walking and particularly when running, and should provide support and a reliable grip when walking and standing. For this reason, very different kinds of shoes are manufactured, these shoes being optimized for their specific use. Persons having to stand for long periods of time prefer shoes with a foot support which reduces the load on the feet. Athletes prefer shoes with a thick, resilient sole which absorbs impact and temporarily stores running energy in a resilient manner. Mountain climbers prefer shoes with a stable sole which will also not be damaged by sharp rocks. Golfers prefer shows with spikes which ensure a good grip. Women generally prefer shoes with a higher heel. Additionally, a requirement for all shoes is that they should be attractive and have a long useful life.
U.S. Pat. Nos. 4,128,950, 4,449,306 and 4,759,136 disclose running shoes for athletes. All of these shoes have a continuous thick, triple-part, resilient elastic sole construction whose heel is raised by a heel wedge. The front edge of the heel wedge ends roughly halfway along the length of the shoe.
U.S. Pat. No. 2,435,976 shows a shoe whose multiple-part sole includes a part comprising a substantially inflexible material. The sole is uniformly curved from the toe to the heel. This shoe allows patients with all artificial leg to walk easily and naturally. Such a shoe cannot be worn by normal, healthy individuals.
U.S. Pat. No. 4,463,505 shows a boot with a multiple-part sole in which are incorporated special orthopedic supports for patients with foot ailments.
U.S. Pat. No. 2,603,891 shows a washable slipper with a multiple-part sole, the insole being made of multiple layers of a mixture of cork and rubber which are glued together. The upper side of the insole facing the foot is completely flat and the foot is not supported.
U.S. Pat. No. 617,701 discloses the use of thin insoles of cork in shoes. Tile foot is not supported by this insole.
U.S. Pat. No. 4,852,273 discloses a two-part sole in which both parts are made of foamed plastic and are glued together. The insole has a foot support and a plurality of small and large channels, particularly in the metatarsal region of the foot. The outsole is thick, resiliently elastic and is provided with a special profiling. The outer surface is beveled under the toes and under tile heel. Tile sole of the wearer's foot is actively ventilated during walking by means of the combined action of the outsole and insole so as to prevent the foot from perspiring.